You can steal cars at the north of the park because you'll find a few of them there. Make sure to do this while no cops are looking. Once you've parked the car, type in Bucky Sligo on the computer.

As soon as you get there, you should be able to easily keep up with his slow driving as he makes his way through back-alleys and fences. If tries to get inside the house, shoot him before he successfully does. Then, start blasting using your gun. You must work quickly because you have the cops right on your tail. The last thing you want right now is to get arrested, so you can shoot at them if you have to. This is okay as long as no cops see you shooting up the house. If the cops are after you, even before you clean out all the thugs, then you might want to escape through the back door and run on foot until you are safely out of their range, or until you get a car to escape.

After shaking off the cops, you will get a call from Derrick telling you that it was a mission completed.